Ultraprocessed Foods Linked to Silent Brain Injury

Higher ultraprocessed food (UPF) intake was associated with silent vascular brain injury in middle-aged adults without cardiovascular disease, with no apparent effect on cognition. In a cross-sectional study of 8783 adults aged 35-69 years, those in the highest quartile of UPF intake had 40% higher odds of MRI-defined covert brain infarcts or high white matter hyperintensity burden than those in the lowest quartile. They also had greater total body fat and visceral adiposity.The findings are “clinically relevant because vascular brain injury can be present long before symptoms emerge,” lead author Russell J. de Souza, RD, ScD, McMaster University, Hamilton, Ontario, Canada, told Medscape Medical News."Although we observed no differences in cognitive performance, a substantial body of evidence shows that greater burdens of white matter hyperintensities and silent brain infarcts are associated with lower cognitive performance and a higher risk of future stroke," he noted.The study was published online October 15 in JAMA Network Open.Hidden DamageUPFs account for more than half of daily energy intake in many high-income countries and have been linked to obesity, cardiometabolic disease, and poor brain health. However, few studies have examined whether UPF intake is associated with subclinical cerebrovascular injury in midlife before cognitive impairment becomes apparent. To investigate, the researchers used baseline data from two Canadian cohort studies, the Canadian Alliance for Healthy Hearts and Minds, and the Prospective Urban and Rural Epidemiology-MIND study (PURE-MIND). They included 8783 adults without cardiovascular disease (mean age, 57.7 years; 56.6% women). Dietary intake was assessed using validated food-frequency questionnaires, and UPFs were classified according to the NOVA system, which categorizes foods by the extent and purpose of industrial processing. Examples include packaged snack foods, sugary breakfast cereals, soft drinks, instant noodles, and ready-to-eat frozen meals.UPF consumption was expressed as servings per 2000 kcal/d, with participants divided into quartiles. Mean consumption ranged from 3.1 servings per 2000 kcal/d in the lowest quartile to 12.8 in the highest.Overall, 9.2% of participants had MRI evidence of vascular brain injury, defined as covert brain infarcts or a high burden of white matter hyperintensities. The prevalence of vascular brain injury was 11.3% in the highest-consumption group compared with 8.1% in the lowest.After adjustment for demographic, socioeconomic, lifestyle, and cardiometabolic risk factors, participants in the highest UPF consumption quartile had significantly higher odds of subclinical vascular brain injury than those in the lowest quartile (adjusted odds ratio [aOR], 1.40; 95% CI, 1.10-1.77; P for trend = .009). Associations with the individual components were directionally similar but did not consistently reach statistical significance. In sex-stratified analyses, the association with vascular brain injury was stronger in women (aOR, 1.78; 95% CI, 1.27-2.48) than in men (aOR, 1.08; 95% CI, 0.76-1.54; P for interaction = .04). However, the researchers cautioned that these exploratory findings require confirmation.Cognition Unaffected — For NowHigher UPF intake was also associated with greater adiposity. Participants in the highest quartile had 1.7 percentage points more body fat and 5.7 mL more visceral adipose tissue than those in the lowest quartile, but no significant difference in hepatic fat fraction. In the primary analyses, UPF intake was not associated with performance on the Montreal Cognitive Assessment (MoCA) or the Digit Symbol Substitution Test (DSST).Although the association was significant when UPF consumption was expressed as servings per 2000 kcal/d, it was not significant when measured as a percentage of total caloric intake or total food servings.De Souza said the measures capture different aspects of consumption. Servings may better reflect how often and how many kinds of UPFs people eat, whereas energy-based measures emphasize their caloric contribution.“The consistency of direction is reassuring, but the sensitivity to exposure definition means the finding should be replicated before strong causal inferences are made,” he said. Other limitations included the cross-sectional design, reliance on a single food-frequency questionnaire, possible residual confounding, and the limited sensitivity of brief cognitive tests in a relatively healthy, highly educated cohort. The investigators noted that longitudinal studies are needed to determine whether UPF intake contributes to vascular brain injury and later cognitive decline. That follow-up, including repeat MRI scans, is already underway, de Souza said. Another Link in the ChainThe new findings add to a growing body of research on UPFs and brain health.They are consistent with previous studies linking UPF consumption to stroke and cognitive impairment, W. Taylor Kimberly, MD, PhD, chief of neurocritical care at Mass General Brigham and professor of neurology at Harvard Medical School, Boston, told Medscape Medical News.The study extends that evidence to earlier signs of cerebrovascular disease, he said.Middle-aged adults may already be accumulating vascular brain injury years before cognitive effects appear, Kimberly said, which could explain why UPF intake wasn’t linked to cognitive performance.”When counseling patients, Kimberly said he explains that diet can take many years to affect health and that no study has yet proven that cutting back on UPFs improves outcomes."Current studies report an association but don't prove the cause-effect relationship. That being said, it's very reasonable to make dietary changes by reducing UPF intake," he added. Most studies of UPFs and health have shown unfavorable outcomes, and the correlation should be taken seriously, said Marion Nestle, PhD, MPH, professor emerita of nutrition, food studies, and public health at New York University, New York City, who was not involved in the research. “Here’s one more,” she said.The study was supported by Canadian public and nonprofit funding sources. The underlying cohorts also received unrestricted industry funding. Author disclosures are available with the original study publication. Kimberly and Nestle reported no relevant disclosures.